Title

Author

Abstract

"Geochemical analysis of stream sediments from the Big River Watershed of southeastern Missouri indicates that they contain elevated concentrations of contaminant metals such as Pb. Zn, Cu. Co, Ni and Cd. The elevated concentrations are derived from natural exposures of metal enriched strata and the numerous mine tailings piles and water seeps created as a result of about 300 years of lead-zinc mining in the “Old Lead Belt”. Galena (PbS), sphalerite (ZnS), and pyrite (FeS2) are the primary sulfides found in the tailings piles and Scanning Electron Microscopy analysis of individual metallic sediment particles collected at intervals downstream from the Desloge tailings was conducted to investigate the survivability of the sulfides in the stream as well as determine what phases the contaminant metals associate with at proximal and distal locations on the Big River. Pyrite was found up to ~6 nautical kilometers downstream from the tailings, while galena and sphalerite phases were more durable in the river system and found up to ~13 nautical kilometers downstream. Analysis of sedimentary particles collected further downstream indicates that contaminant metals such as Pb. Zn, Cu, Cd, Ni and Ba tend to sorb onto Si, Fe and Mn oxide and/or oxyhydroxide phases. At Brynesville (~84 miles/134 kilometers downstream from the Desloge Tailings Pile), the Pb concentration of 1423 ppm is ~11 times higher than the control site value of 123 ppm Pb, implying that the release of galena and its dissolution components from the tailings still has a strong influence, even on the most distal sample sites in the stream. At the distal sampling sites, Pb and Zn is concentrated in the silt+clay size fraction, which is likely due to upstream dissolution of sulfides and the subsequent adsorption of dissolved Pb and Zn ions onto smaller particles of Al- Si- Fe- Mn oxide and/or oxyhydroxide phases"--Abstract, page iii.

Advisor(s)

Wronkiewicz, David J.

Committee Member(s)

Hogan, John PatrickWang, Jiaming

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

M.S. in Geology and Geophysics

Sponsor(s)

United States. Environmental Protection Agency. Center for the Study of Metals in the Environment